The advantages of ultrasound include the real time imaging capability, low cost, flexibility in its application, and the fact that no ionizing radiation is used. However, non-enhanced ultrasound, including the commonly used gray-scale ultrasound imaging, may not be able to visualize a particular target (e.g., a tumor) with the desired contrast, and in some cases, may not visualize the target at all.
Contrast-enhanced ultrasound (CEUS) can provide superior visualization of tumors, vascularity, and other tissues of interest compared to non-contrast enhanced ultrasound imaging. However, the contrast enhancement after injection of the contrast agent is a transient phenomenon. After injection, there is typically a first phase where the concentration of contrast agent in the target area increases. This phase is called wash-in time. The concentration of the contrast agent (which corresponds to the intensities in the contrast-enhanced images) increases until a peak is reached. The time between injection and peak is called time-to-peak. Subsequently, the contrast agent is washed out and the intensity in the contrast-enhanced images decreases again. This dynamic behavior yields a characteristic time intensity curve.
Current work flow is typically such that the ultrasound images are first acquired, then transferred to a work station and finally quantitatively analyzed on the work station. The analysis of the images thus occurs after the acquisition of the images. Typical file sizes from contrast enhanced ultrasound acquisition are on the order of several MB. A typical study is made up of many files, which can result in several GB of overall data.
U.S. Pat. No. 5,743,266 discloses a method for producing real-time colorized, contrast enhanced images from a sequence of grey-scale video images obtained during diagnostic ultrasound. The particular colorizing scheme varies according to which information parameter is desired to be displayed in real-time.